ipTIME-device uImage firmware Header Rewrite Script

rewrite.py

#!/usr/local/bin/python

#######################################################
# ipTIME uImage Firmware Header Rewriter
#######################################################

import os, zlib
import binascii
import sys
from struct import *

HEADER_FORMAT = '!7L4B32s'    ### (Big-endian, 7 ULONGS, 4 UCHARs, 32-byte string)
HEADER_SIZE=calcsize(HEADER_FORMAT)    ### Should be 64-bytes

name = 'a1004ns'
name_size = 32

################################################################################
###
### parseHeader(fh, offset=0) - Parse uImage header located at offset in file
###
### Parameters:   fh:      file handle
###               offset:  Optional location of header within file
###
### Returns:      Dictionary of header information
###
def parseHeader(fh, offset=0):
    ### Save current position and seek to start position
    startpos = fh.tell()
    fh.seek(offset)

    try:
        block = fh.read(HEADER_SIZE)
    except IOError:
        print("File read error")
        exit(1)

    ### Names of fields in the image header
    keys = ['magic', 'headerCrc', 'time', 'size', 'loadAddr', 'entryAddr',
            'dataCrc', 'osType', 'arch', 'imageType', 'compression', 'name']

    ### Unpack the header into a dictionary of (key,value) pairs
    values = unpack(HEADER_FORMAT, block)
    hd = dict(zip(keys, values))

    ### if Multi-file image, append file information
    if hd['imageType'] == 4:
        hd['files'] = getMultiFileLengths(fh, fh.tell())
    ### Restore saved file position
    fh.seek(startpos)
    return hd

def calculateHeaderCrc(hd):
    ### Re-pack the list into a binary string
    ### Must calclate header CRC with CRC field set to 0.
    header = pack(HEADER_FORMAT, hd['magic'], 0, hd['time'], hd['size'],\
        hd['loadAddr'], hd['entryAddr'], hd['dataCrc'], hd['osType'], \
        hd['arch'], hd['imageType'], hd['compression'], hd['name'])
    return zlib.crc32(header)

filename = sys.argv[1]
modelname = sys.argv[2]
size = -1
data = None

try:
    size = os.path.getsize(filename)
except IOError:
    print("inavlid filename:", filename)
    exit(1)

if size < HEADER_SIZE:
    print("File too small!  Not a uImage file.")
    exit(1)

f = open(filename, "rb")

header = parseHeader(f)
header['name'] = str.encode(modelname)
header_crc = (calculateHeaderCrc(header) & 0xffffffff)

print(hex(header['headerCrc']), 'to', hex(header_crc))
print('Rewriting header...')

header_crc = header_crc.to_bytes(4, byteorder='big')

modelname_bytes = str.encode(modelname + ('\0'*(32-len(modelname))))

f.close()
f = open(filename, "rb")
header_bytes = f.read(HEADER_SIZE)
header_bytes = header_bytes[:4] + header_crc + header_bytes[8:32] + modelname_bytes

print(binascii.hexlify(header_bytes))
f.close()

with open('new_' + filename, 'wb') as fw:
	fw.write(header_bytes)
	with open(filename, 'rb') as fr:
		fr.seek(HEADER_SIZE)
		fw.write(fr.read(size))

• ipTIME 기기의 펌웨어 체크섬은 CRC 검사 및 모델내임 검사를 같이 하므로, 모델네임을 기기로 바꿔서 CRC 체크섬을 재작성해주는 스크립트임.